#1: THE BASICS

There’s more than one arc flash hazard

Arc flash is scary because you have to deal with more than one hazard at the same time.

Just take a quick look at this image… you can see that there are a lot of things you need to consider.

Dealing with the heat.

(click to enlarge)

The heat will impact your entire body and everything you need to wear so let’s take a look a this first.

You need to make sure you’ve got yourself covered with something that will protect you from the heat energy… don’t get this confused with the fire ball, that will come later.

You need something that can absorb the heat and protect your skin from the worst sun burn you would have ever gotten… this “sunburn” would be to the tune of 20,000 degrees Celsius.

The material used for heat protection has to have an Arc Thermal Performance Value (ATPV) or a Breakopen Threshold Energy (EBT) that is suitable for the arc flash exposure… more on this later.

Most times I’m looking for an ATPV of at least 8.

Seems easy...what's the trick?

The trick is that you have to know what the potential incident energy of the equipment you are working on is.

One way to find out is by performing arc flash hazard calculations… this is by far the best way to understand just how much heat energy you are up against.

The heat energy is measured in calories per centimeter squared or cal/cm^2.

Essentially if you are wearing something with an ATPV rating that is a higher number than the cal/cm^2 then you will be fine.

#2: HEAD PROTECTION

If there is one part of my body I want to protect from severe burns, which would alter the way I look for the rest of my life, it’s my face.

Too many arc flash incidents lead to people having 2nd and 3rd degree burns to their face, ears and head.

Not to mention, they are at risk of going blind from the extremely bright light generated from the arc flash as well as deaf from the loud sound produced which usually hovers around the 160 dB mark (that’s like standing next to fighter jet on the runway… with no hearing protection).

So firsts let’s make sure we understand all the hazards our face, neck, eyes, ears and head have to deal with.

We already mentioned the heat

Like I said earlier… make sure all your head protection (faceshield, balaclava, or arc flash hood) have an ATPV that is suitable for the arc flash hazard.

You’ve got a couple options to choose from.

Your two choices to protect from the heat will be either an arc flash face shield with balaclava or an arc flash hood (which really does it all).

Arc Rated Faceshield & Balaclava

Arc Flash Hood

Dealing with the light.

During the arc flash there is an insane amount of light produced and if you ever talk to an arc flash survivor they will almost always tell you they were temporarily blinded (if not permanently)… which is never a good thing when you are on fire.

To make sure you have adequate protection for your eyes you’ll need to wear an arc flash faceshield.

The technology in the faceshield is designed to protect your eyes from the intense and harmful light emitted from the arc flash (not to mention the heat energy).

This is why the faceshields are tinted.. what’s really cool is that you no longer have to struggle with dark orange and green tinted faceshields as the technology has gotten that much better.

Find one with a grey tint that looks similar to the one in this picture.

What about the fireball?

Arc rated protective equipment not only needs to absorb the heat energy from the arc flash but it also needs to have the Flame-Resistant (FR) properties similar to what you would wear in case of flash fire.

Basically, if you are in an arc flash, you don’t want your head (or anything you are wearing on your head) to catch on fire.

If the arc flash faceshield & balaclava or arc flash hood have an ATPV rating then it will also have the flame-resistant properties you need.

What?! I can’t hear you…

The sound produced during an arc flash is very loud.

In order to combat that you’ll need to wear hearing protection.

There are different types of hearing protection on the market but ear canal inserts are really the most practical.

You need to wear these underneath your balaclava or arc flash hood so having the big earmuffs on is not going to work.

That it covers your entire body (don’t roll up sleeves or unbutton the shirt);

That it looks good… just kidding;

That it’s comfortable… you don’t want to give yourself any excuse not to wear it.

What about cotton? Electricians always wore cotton…

Ahh… watch this…

That’s a resounding NO for those of you who didn’t watch.

What about layering?

So you want to wear you arc flash jacket over your arc flash coveralls?

Fantastic!

There is never a case when doing this will reduce your protection.

But I thought you were not supposed to do that?… you say.

Well, the thing is in order to know exactly what the ATPV of the layered system would be you technically need to test it… so rumor was that you couldn’t just simply add the two ATPV together to come up with a new rating.

But here is a little secret.

It will always be higher… every test that I’ve ever seen done came back higher than the two added together. Probably due to the air gap between the clothing.

Does some heat still get through?

Technically a shirt rated 8 ATPV when exposed to an arc flash of 8 cal/cm^2 has potential to allow through enough heat energy to cause the onset of a second degree burn… go figure?

But here is a couple things that will make you feel better about this.

It will only happen 50% of the time;

At any one time there is less than 30% of your body actually in contact with your clothing… so most of it is protected by air;

Arc flash calculations are slightly conservative (although this might be changing)… so you should be fine.

The easy solution…

Always wear a bit more than what’s on the label.

#5: FOOT PROTECTION

Foot protection is pretty straightforward for arc flash.

Wear leather boots… not ones that will melt.

That’s about all you need to know.

#6: SELECTION METHODS

We’ve already touched on this a bit here… but for the most part you have two ways to determine what arc flash PPE you need for the job.

The incident energy method; and

The category method.

Each method has there flaws… but we will go over them here and you can decide how you want to proceed.

The incident energy method

From an ease-of-use and simplicity standpoint for selecting your clothing this is the way to go.

Inherent FR fabrics are made of fibers in which the FR properties are naturally part of the polymer backbone and can never be worn away or washed out. The actual structure of the fiber itself is non-flammable; therefore, the flame trait is permanent.

The first thing you want to do is check what type of clothing you have.

If it’s treated then you are going to need to take special care of how it’s washed.

Might sound like a cop-out but you’ll need to follow the specifications from your clothing manufacturer if you want to get it right.

As for inherent FR, in my opinion, it’s not as critical but you’ll still want to stay away from cleaning supplies which could damage the arc rating capabilities of the clothing.

You can also pick up a copy of ASTM F1449 (Standard Guide for Industrial Laundering of Flame, Thermal, and Arc Resistant Clothing) for more information.